As is well known, para-alkyl primary aromatic amines in addition to being useful as chemical intermediates are also useful in a variety of other applications. For examples, they are used in lubricants as antioxidants and in fuels as anti-knock agents, to mention a few.
Methods for alkylating primary aromatic amines typically result in the formation primarily of the ortho and meta isomers of the alkyl aromatic amines along with N-alkylated species. Although the ortho and meta isomers have somewhat similar properties to the para-isomers, most often the properties of the para-isomers are significantly better than the others making the para-isomer the compound of choice in many applications. Consequently attempts have been made to produce para-alkylated aromatic amines in preference to the ortho and meta compounds. In this regard mention is made British Patent 846,226 and Canadian Patent 663,698 each of which disclose processes that result in the formation of mixtures relatively high in para alkylated phenyl amines. For example, in the alkylation of aniline with isobutylene by the process of British Patent 846,226 the p-tertiary butylaniline is obtained (about 85 to 88% based on moles of aniline converted) with varying amounts of o-tertiary butylaniline, N-tertiary butylaniline and di-tertiary butylaniline. In the process of Canadian Patent 663,698 the alkylation of aniline with isobutylene was reported as producing significant amount of di-tertiary butylaniline along with the para-tertiary butylaniline.
One object of the present invention is to provide an improved method in forming para alkylated primary aromatic amines.
Another object of the present invention is to provide a method for alkylating primary aromatic amines which favors the formation of the para alkylated derivative.
Another object of the present invention is to provide a method for forming para-alkylated primary aromatic amines in increased yields.
Other objects of the invention will become apparent from the description hereinafter.